Yoda1 and phosphatidylserine exposure in red cells from patients with sickle cell anaemia

Phosphatidylserine (PS) exposure is increased in red cells from sickle cell anaemia (SCA) patients. Externalised PS is prothrombotic and attractive to phagocytes and activated endothelial cells and thus contributes to the anaemic and ischaemic complications of SCA. The mechanism of PS exposure remains uncertain but it can follow increased intracellular Ca²⁺ concentration ([Ca²⁺]_i). Normally, [Ca²⁺]_i is maintained at very low levels but in sickle cells, Ca²⁺ permeability is increased, especially following deoxygenation and sickling, mediated by a pathway sometimes called P_sickle. The molecular identity of P_sickle is also unclear but recent work has implicated the mechanosensitive channel, PIEZO1. We used Yoda1, an PIEZO1 agonist, to investigate its role in sickle cells. Yoda1 caused an increase in [Ca²⁺]_i and PS exposure, which was inhibited by its antagonist Dooku1 and the PIEZO1 inhibitor GsMTx4, consistent with functional PIEZO1. However, PS exposure did not necessitate an increase in [Ca²⁺]_i. Two PKC inhibitors were also tested, chelerytherine chloride and calphostin C. Both reduced PS exposure whilst chelerytherine chloride also reduced Yoda1-induced increases in [Ca²⁺]_i. Findings are therefore consistent with the presence of PIEZO1 in sickle cells, able to mediate Ca²⁺ entry but that PKC was also involved in both Ca²⁺ entry and PS exposure.

Associations of insulin-like growth factor-I and insulin-like growth factor binding protein-3 with bone quality in the general adult population

OBJECTIVE

Growth hormone (GH) and its main mediator, insulin-like growth factor-I (IGF-I), play a significant role in bone metabolism. The relations between IGF-I and bone mineral density (BMD) or osteoporosis have been assessed in previous studies but whether the associations are sex-specific remains uncertain. Moreover, only a few studies examined bone quality assessed by quantitative ultrasound (QUS). We aimed to investigate these associations in the general population of north-east Germany.

DESIGN AND MEASUREMENTS

Data from 1759 men and 1784 women who participated in the baseline examination of the Study of Health in Pomerania (SHIP)-Trend were used. IGF-I and IGF-binding protein-3 (IGFBP-3) concentrations were measured on the IDS-iSYS multidiscipline automated analyser (Immunodiagnostic Systems Limited). QUS measurements were performed at the heel (Achilles InSight, GE Healthcare). Sex-specific linear and multinomial logistic regression models adjusted for potential confounders were calculated.

RESULTS

Linear regression analyses revealed significant positive associations between IGF-I and IGF-I/IGFBP-3 ratio, a marker for free IGF-I, with all QUS parameters in men. Among women, we found an inverse association between IGF-I and the QUS-based fracture risk but no association with any other QUS parameter. There was no association between IGFBP-3 and the QUS-based fracture risk.

CONCLUSIONS

Our data suggest an important role of IGF-I on bone quality in men. The observed association of IGF-I with the QUS-based stiffness index and QUS-based fracture risk in this study might animate clinicians to refer patients with low IGF-I levels, particularly men, to a further evaluation of risk factors for osteoporosis and a detailed examination of the skeletal system.

Physiological Aldosterone Concentrations Are Associated with Alterations of Lipid Metabolism: Observations from the General Population

OBJECTIVE

Aldosterone and high-density lipoprotein cholesterol (HDL-C) are involved in many pathophysiological processes that contribute to the development of cardiovascular diseases. Previously, associations between the concentrations of aldosterone and certain components of the lipid metabolism in the peripheral circulation were suggested, but data from the general population is sparse. We therefore aimed to assess the associations between aldosterone and HDL-C, low-density lipoprotein cholesterol (LDL-C), total cholesterol, triglycerides, or non-HDL-C in the general adult population.

METHODS

Data from 793 men and 938 women aged 25-85 years who participated in the first follow-up of the Study of Health in Pomerania were obtained. The associations of aldosterone with serum lipid concentrations were assessed in multivariable linear regression models adjusted for sex, age, body mass index (BMI), estimated glomerular filtration rate (eGFR), and HbA1c.

RESULTS

The linear regression models showed statistically significant positive associations of aldosterone with LDL-C (β-coefficient = 0.022, standard error = 0.010, p = 0.03) and non-HDL-C (β-coefficient = 0.023, standard error = 0.009, p = 0.01) as well as an inverse association of aldosterone with HDL-C (β-coefficient = -0.022, standard error = 0.011, p = 0.04).

CONCLUSIONS

The present data show that plasma aldosterone is positively associated with LDL-C and non-HDL-C and inversely associated with HDL-C in the general population. Our data thus suggests that aldosterone concentrations within the physiological range may be related to alterations of lipid metabolism.

Associations of aldosterone and renin concentrations with inflammation-the Study of Health in Pomerania and the German Conn's Registry

PURPOSE

Chronic inflammation is an age-independent and body mass index-independent contributor to the development of multi-morbidity. Alterations of the renin-angiotensin-aldosterone system are observed within the context of proinflammatory states. We assessed circulating aldosterone, renin, and inflammatory biomarker concentrations in healthy, normotensive subjects and patients with primary aldosteronism.

METHODS

We included 1177 normotensive individuals from the population-based Study of Health in Pomerania (first follow-up, Study of Health in Pomerania-1) and 103 primary aldosteronism patients from the German Conn's Registry. A 1:1 matching for sex, age, body mass index, smoking status, diabetes mellitus, and the estimated glomerular filtration rate was performed to determine whether primary aldosteronism patients exhibit higher inflammatory biomarker concentrations than normotensive controls. The associations of plasma aldosterone concentration or plasma renin concentration with circulating fibrinogen concentrations, white blood cell count, and high sensitive C-reactive protein concentrations in the normotensive sample were determined with multivariable linear and logistic regression analyses.

RESULTS

1:1 matched primary aldosteronism patients demonstrated significantly (p < 0.01) higher plasma aldosterone concentration (198 vs. 47 ng/l), lower plasma renin concentration (3.1 vs. 7.7 ng/l) and higher high sensitive C-reactive protein concentrations (1.5 vs. 1.0 mg/l) than normotensive controls. Within the normotensive cohort, plasma renin concentration but not plasma aldosterone concentration was positively associated with fibrinogen concentrations and white blood cell count. Further, a J-shaped association between plasma renin concentration and high sensitive C-reactive protein concentrations was detected.

CONCLUSIONS

High plasma aldosterone concentration in a primary aldosteronism cohort and high plasma renin concentration in normotensive subjects are associated with increased concentrations of inflammatory biomarkers. This suggests a link between the renin-angiotensin-aldosterone system and inflammatory processes in patients with primary aldosteronism and even in normotensive subjects.

The Association between Bone Quality and Atherosclerosis: Results from Two Large Population-Based Studies

OBJECTIVE

It is highly debated whether associations between osteoporosis and atherosclerosis are independent of cardiovascular risk factors. We aimed to explore the associations between quantitative ultrasound (QUS) parameters at the heel with the carotid artery intima-media thickness (IMT), the presence of carotid artery plaques, and the ankle-brachial index (ABI).

METHODS

The study population comprised 5680 men and women aged 20-93 years from two population-based cohort studies: Study of Health in Pomerania (SHIP) and SHIP-Trend. QUS measurements were performed at the heel. The extracranial carotid arteries were examined with B-mode ultrasonography. ABI was measured in a subgroup of 3853 participants. Analyses of variance and linear and logistic regression models were calculated and adjusted for major cardiovascular risk factors.

RESULTS

Men but not women had significantly increased odds for carotid artery plaques with decreasing QUS parameters independent of diabetes mellitus, dyslipidemia, and hypertension. Beyond this, the QUS parameters were not significantly associated with IMT or ABI in fully adjusted models.

CONCLUSIONS

Our data argue against an independent role of bone metabolism in atherosclerotic changes in women. Yet, in men, associations with advanced atherosclerosis, exist. Thus, men presenting with clinical signs of osteoporosis may be at increased risk for atherosclerotic disease.

Reduced Bone Stiffness in Women Is Associated with Clinical Attachment and Tooth Loss

The authors evaluated the association of reduced bone stiffness of the calcaneus with clinical attachment loss (CAL) and tooth loss. The authors analyzed data from 4,678 subjects (2,384 women), aged 20 to 88 y, from the second follow-up of the population-based Study of Health in Pomerania (SHIP-2) and the baseline examination of the SHIP-Trend cohort. Bone stiffness, characterized by the stiffness index (SI) and the osteoporotic fracture risk (OFR), was assessed by quantitative ultrasound of the heel. SI and OFR were significantly associated with the mean CAL in women. While 1) the SI showed a significant association with the mean CAL and 2) the OFR with the median number of teeth in just the postmenopausal women, the OFR showed a significant association with mean CAL for both pre- and postmenopausal women. In postmenopausal women, a 10-unit increase in the SI was associated with a decrease in the mean CAL of 0.05 mm (95% confidence interval [CI]: –0.10 to 0.00; P = 0.046). Moreover, the adjusted median number of teeth was 21.4 (95% CI: 20.9 to 21.9) among the postmenopausal women with a low OFR, while it was 19.1 (95% CI: 17.8 to 20.3; P = 0.001) among the postmenopausal women with a high OFR. For the premenopausal women with a low OFR, the mean CAL was 1.60 mm (95% CI: 1.53 to 1.66), while for the premenopausal women with a high OFR, it was 2.24 mm (95% CI: 1.78 to 2.69; P = 0.006). Reduced bone stiffness was associated with clinical attachment and tooth loss in women but not in men.

Prevalence of Malignancies in Patients With Primary Aldosteronism

CONTEXT

Primary aldosteronism (PA) is the most common cause of secondary hypertension. Aldosterone excess can cause DNA damage in vitro and in vivo. Single case reports have indicated a coincidence of PA with renal cell carcinoma and other tumors. However, the prevalence of benign and malignant neoplasms in patients with PA has not yet been studied.

PATIENTS AND DESIGN

In the multicenter MEPHISTO study, the prevalence of benign and malignant tumors was investigated in 335 patients with confirmed PA. Matched hypertensive subjects from the population-based Study of Health in Pomerania cohort served as controls.

RESULTS

Of the 335 PA patients, 119 (35.5%) had been diagnosed with a tumor at any time, and 30 had two or more neoplasms. Lifetime malignancy occurrence was reported in 9.6% of PA patients compared to 6.0% of hypertensive controls (P = .08). PA patients with a history of malignancy had higher baseline aldosterone levels at diagnosis of PA (P = .009), and a strong association between aldosterone levels and the prevalence of malignancies was observed (P = .03). In total, 157 neoplasms were identified in the PA patients; they were benign in 61% and malignant in 25% of the cases (14% of unknown dignity). Renal cell carcinoma was diagnosed in five patients (13% of all malignancies) and was not reported in controls

CONCLUSION

Compared to hypertensive controls, the prevalence of malignancies was positively correlated with aldosterone levels, tended to be higher in PA patients, but did not differ significantly.

Thyrotropin serum levels are differentially associated with biochemical markers of bone turnover and stiffness in women and men: results from the SHIP cohorts

In two large German population-based cohorts, we showed positive associations between serum thyrotropin (TSH) concentrations and the Fracture Risk Assessment score (FRAX) in men and positive associations between TSH concentrations and bone turnover markers in women.

INTRODUCTION

The role of thyroid hormones on bone stiffness and turnover is poorly defined. Existing studies are confounded by differences in design and small sample size. We assessed the association between TSH serum concentrations and bone stiffness and turnover in the SHIP cohorts, which are two population-based cohorts from a region in Northern Germany comprising 2654 men and women and 3261 men and women, respectively.

METHODS

We calculated the bone stiffness index using quantitative ultrasound (QUS) at the calcaneus, employed FRAX score for assessment of major osteoporotic fractures, and measured bone turnover markers, N-terminal propeptide of type I procollagen (P1NP), bone-specific alkaline phosphatase (BAP), osteocalcin, and type I collagen cross-linked C-telopeptide (CTX) in all subjects and sclerostin in a representative subgroup.

RESULTS

There was no association between TSH concentrations and the stiffness index in both genders. In men, TSH correlated positively with the FRAX score both over the whole TSH range (p < 0.01) and within the reference TSH range (p < 0.01). There were positive associations between TSH concentrations and P1NP, BAP, osteocalcin, and CTX (p < 0.01) in women but not in men. There was no significant association between TSH and sclerostin levels.

CONCLUSIONS

TSH serum concentrations are associated with gender-specific changes in bone turnover and stiffness.

Cation Homeostasis in Red Cells From Patients With Sickle Cell Disease Heterologous for HbS and HbC (HbSC Genotype)

Sickle cell disease (SCD) in patients of HbSC genotype is considered similar, albeit milder, to that in homozygous HbSS individuals--but with little justification. In SCD, elevated red cell cation permeability is critical as increased solute loss causes dehydration and encourages sickling. Recently, we showed that the KCl cotransporter (KCC) activity in red cells from HbSC patients correlated significantly with disease severity, but that in HbSS patients did not. Two transporters involved in red cell dehydration, the conductive channels Psickle and the Gardos channel, behaved similarly in red cells from the two genotypes, but were significantly less active in HbSC patients. By contrast, KCC activity was quantitatively greater in HbSC red cells. Results suggest that KCC is likely to have greater involvement in red cell dehydration in HbSC patients, which could explain its association with disease severity in this genotype. This work supports the hypothesis that SCD in HbSC patients is a distinct disease entity to that in HbSS patients. Results suggest the possibility of designing specific treatments of particular benefit to HbSC patients and a rationale for the development of prognostic markers, to inform early treatment of children likely to develop more severe complications of the disease.

Positive Association Between Adipose Tissue and Bone Stiffness

Obesity is often considered to have a protective effect against osteoporosis. On the other hand, several recent studies suggest that adipose tissue may have detrimental effects on bone quality. We therefore aimed to investigate the associations between body mass index (BMI), waist circumference (WC), visceral adipose tissue (VAT) or abdominal subcutaneous adipose tissue (SAT), and bone stiffness. The study involved 2685 German adults aged 20-79 years, who participated in either the second follow-up of the population-based Study of Health in Pomerania (SHIP-2) or the baseline examination of the SHIP-Trend cohort. VAT and abdominal SAT were quantified by magnetic resonance imaging. Bone stiffness was assessed by quantitative ultrasound (QUS) at the heel (Achilles InSight, GE Healthcare). The individual risk for osteoporotic fractures was determined based on the QUS-derived stiffness index and classified in low, medium, and high risk. Linear regression models, adjusted for sex, age, physical activity, smoking status, risky alcohol consumption, diabetes, and height (in models with VAT or abdominal SAT as exposure), revealed positive associations between BMI, WC, VAT or abdominal SAT, and the QUS variables broadband-ultrasound attenuation or stiffness index. Moreover, BMI was positively associated with speed of sound. Our study shows that all anthropometric measures including BMI and, WC as well as abdominal fat volume are positively associated with bone stiffness in the general population. As potential predictors of bone stiffness, VAT and abdominal SAT are not superior to easily available measures like BMI or WC.

Adiposity measures and vitamin D concentrations in Northeast Germany and Denmark

BACKGROUND

Body mass index (BMI) and serum 25-hydroxy vitamin D3 (25OHD) concentrations are inversely related. As BMI contains only limited information regarding body fat distribution, we aimed to analyze the cross-sectional associations of abdominal visceral or subcutaneous adipose tissue, next to common adiposity measures, with the 25OHD concentration.

METHODS

Data were obtained from three cohorts of two large epidemiological studies in the northeast of Germany (Study of Health in Pomerania, SHIP-1 and SHIP-Trend), and in Denmark (Health2006). The study populations included adult men and women from the general population (N = 3072 SHIP-1, N = 803 SHIP-Trend, N = 3195 Health2006). Visceral and subcutaneous adipose tissue were quantified by magnetic resonance imagining (SHIP-Trend) or ultrasound (Health2006). Common adiposity measures, including BMI, waist circumference, waist-to-hip ratio, waist-to-height ratio, body surface area, and body fat percentage were determined by standardized methods in SHIP-1 and Health2006.

RESULTS

The average study participant was overweight (median BMI 27.4, 26.6, and 25.2 kg/m(2) in SHIP-1, SHIP-Trend, and Health2006, respectively). Visceral and subcutaneous adipose tissue as well as the common adiposity measures were inversely associated with serum 25OHD concentrations in linear regression models adjusted for age, sex, alcohol consumption, physical activity, smoking status, and month of blood sampling.

CONCLUSIONS

Next to common adiposity measures, also abdominal visceral or subcutaneous adipose tissue are inversely associated with serum 25OHD concentrations in the general adult population.

Lower bone turnover markers in metabolic syndrome and diabetes: the population-based Study of Health in Pomerania

BACKGROUND AND AIMS

Accumulating evidence demonstrates an important interaction between bone and energy metabolism. We aimed to study the associations of three bone turnover markers (BTM: osteocalcin, beta-crosslaps, procollagen type 1 N-terminal propeptide) as well as of 25-hydroxyvitamin D and parathyroid hormone with metabolic syndrome (MetS) or type 2 diabetes mellitus (T2DM) in a large population-based cohort.

METHODS AND RESULTS

This cross-sectional study comprised 2671 adult men and women participating in the first follow-up of the population-based Study of Health in Pomerania (SHIP-1). Multivariable logistic regression analyses were performed to assess sex-specific associations between the BTMs, 25-hydroxyvitamin D or parathyroid hormone and metabolic disease. All models were adjusted for age, body mass index, smoking status, physical activity, estimated glomerular filtration rate and month of blood sampling. The models for women were further adjusted for menopausal status. Higher BTM or 25-hydroxyvitamin D concentrations were associated with significantly lower odds for metabolic disease, while there was no association between parathyroid hormone and MetS or T2DM.

CONCLUSION

Our results contribute to the accumulating evidence of a cross-sectional association between high BTM or 25-hydroxyvitamin D concentrations and a lower prevalence of MetS or T2DM. Further research is necessary to evaluate the mechanisms underlying these results.

Effects of o-vanillin on K⁺ transport of red blood cells from patients with sickle cell disease

Aromatic aldehydes like o-vanillin were designed to reduce the complications of sickle cell disease (SCD) by interaction with HbS, to reduce polymerisation and RBC sickling. Present results show that o-vanillin also directly affects RBC membrane permeability. Both the K(+)-Cl(-) cotransporter (KCC) and the Ca(2+)-activated K(+) channel (or Gardos channel) were inhibited with IC50 of about 0.3 and 1 mM, respectively, with activities almost completely abolished by 5 mM. Similar effects were observed in RBCs treated with the thiol reacting reagent N-ethylmaleimide or with the Ca(2+) ionophore A23187, to circumvent any action via HbS polymerisation. The deoxygenation-induced cation conductance (sometimes termed P(sickle)) was partially inhibited, whilst deoxygenation-induced exposure of phosphatidylserine was completely abrogated. Na(+)/K(+) pump activity was also reduced. Notwithstanding, o-vanillin stimulated K(+) efflux through an unidentified pathway and resulted in reduction in cell volume (as measured by wet weight-dry weight). These actions are relevant to understanding how aromatic aldehydes may affect RBC membrane permeability per se as well as HbS polymerisation and thereby inform design of compounds most efficacious in ameliorating the complications of SCD.

Prospective Study of Serum 25-hydroxy Vitamin D and Tooth Loss

Vitamin D deficiency and oral diseases (periodontitis, caries, and tooth loss) are highly prevalent in Germany. Previous studies suggested that vitamin D might be a modifiable and protective factor for periodontitis, caries, and tooth loss. However, prospective studies investigating such associations are limited. We explored the association between the concentration of serum 25-hydroxy vitamin D (25OHD) and incidence of tooth loss, progression of clinical attachment loss (CAL) ≥ 3 mm, and progression of restorative and caries status in a population-based longitudinal study. We analyzed data from 1,904 participants from the Study of Health in Pomerania with a five-year follow-up. Generalized estimating equation models were applied to evaluate tooth-specific associations between serum 25OHD and incidence of tooth loss, progression of CAL ≥ 3 mm, and progression of restorative and caries status. Age, sex, education, smoking status, alcohol drinking, waist circumference, dental visit frequency, reasons of dental visit, vitamin D or calcium supplements, and season of blood draw were considered as confounders. Serum 25OHD was inversely associated with incidence of tooth loss. A significant dose-response relationship (p = .0022) was observed across the quintiles of serum 25OHD. After adjusting for multiple confounders, each 10-µg/L increase of serum 25OHD was associated with a 13% decreased risk of tooth loss (risk ratio: 0.87; 95% confidence interval: 0.79, 0.96). The association was attenuated for changes of CAL ≥ 3 mm when adjusting for multiple confounders. No significant association was found between serum 25OHD and caries progression. Vitamin D might be a protective factor for tooth loss. The effect might partially be mediated by its effect on periodontitis.

Reference intervals for serum concentrations of three bone turnover markers for men and women

OBJECTIVE

Bone turnover markers (BTMs) reflect the metabolic activity of bone tissue and can be used to monitor osteoporosis therapy. To adequately interpret BTMs, method-specific reference intervals are needed. We aimed to determine reference intervals for serum concentrations of intact amino-terminal propeptide of type I procollagen (PINP), bone-specific alkaline phosphatase (BAP) and carboxy-terminal telopeptide of type I collagen (CTX).

MATERIAL AND METHODS

We established a healthy reference population of 1107 men as well as 382 pre- and 450 postmenopausal women, who participated in the first follow-up of the Study of Health in Pomerania. Serum PINP, BAP and CTX concentrations were measured on the IDS-iSYS Automated System (Immunodiagnostic Systems, Frankfurt am Main, Germany). The reference interval was defined as the central 95% range. We determined age-specific reference intervals for PINP, BAP, and CTX for men by quantile regression. Reference intervals for women were age-independent.

RESULTS

Reference intervals for men for PINP and CTX decreased with age (25-29year-old men: PINP 31.1-95.9ng/mL, CTX 0.12-0.83ng/mL; 75-79year-old men: PINP 15.7-68.1ng/mL, CTX 0.05-0.58ng/mL). The reference interval for men for BAP did not significantly change with age (25-29year-old men: 7.4-27.7ng/mL; 75-79year-old men: 7.6-24.4ng/mL). The reference intervals for 30-54year-old premenopausal women were: PINP 19.3-76.3ng/mL, BAP 6.0-22.7ng/mL, and CTX 0.05-0.67ng/mL. The reference intervals for 50-79year-old postmenopausal women were: PINP 18.2-102.3ng/mL, BAP 8.1-31.6ng/mL, and CTX 0.09-1.05ng/mL.

CONCLUSION

An intensively characterized, large reference population free of bone-related diseases allowed us to determine robust reference intervals for serum concentrations of PINP, BAP and CTX. Our normative data may aid to interpret bone turnover in adult men and pre- and postmenopausal women.

Identification of the Ca²⁺ entry pathway involved in deoxygenation-induced phosphatidylserine exposure in red blood cells from patients with sickle cell disease

Phosphatidylserine (PS) exposure in red blood cells (RBCs) from sickle cell disease (SCD) patients is increased compared to levels in normal individuals and may participate in the anaemic and ischaemic complications of SCD. Exposure is increased by deoxygenation and occurs with elevation of intracellular Ca²⁺ to low micromolar levels. The Ca²⁺ entry step has not been defined but a role for the deoxygenation-induced pathway, P_sickle, is postulated. Partial P_sickle inhibitors 4-acetamido-4′-isothiocyanostilbene-2,2′-disulphonic acid (SITS), 4,4′-dithiocyano-2,2′-stilbene-disulphonic acid (DIDS) and dipyridamole inhibited deoxygenation-induced PS exposure (DIDS IC₅₀, 118 nM). Inhibitors and activators of other pathways (including these stimulated by depolarisation, benzodiazepines, glutamate and stretch) were without effect. Zn²⁺ and Gd³⁺ stimulated PS exposure to high levels. In the case of Zn²⁺, this effect was independent of oxygen (and hence HbS polymerisation and RBC sickling) but required extracellular Ca²⁺. The effect was completely abolished when Zn²⁺ (100 μM) was added to RBCs suspended in autologous plasma, implying a requirement of high levels of free Zn²⁺.

Osteocalcin is associated with testosterone in the general population and selected patients with bone disorders

Research in the last decade has revealed that bone is not only a target tissue for numerous circulating hormones but functions as an endocrine organ itself. As a recent study demonstrated a stimulatory effect of the osteoblast-derived hormone osteocalcin (OCN) on testosterone production in mice, we investigated whether such an association can be replicated in humans. We used data from 1338 men (25-86 years) in the population-based epidemiological Study of Health in Pomerania and from 110 male outpatients with bone disorders (18-85 years) for the study. We analysed cross-sectional associations between OCN and total testosterone serum concentrations (TT), as well as associations between further markers of bone turnover [bone-specific alkaline phosphatase (BAP), serum C-terminal telopeptides of Type I collagen (CTX), urinary deoxypyridinoline] and TT using ordinary least square (OLS) regression models. Multivariable OLS models revealed a positive association between OCN and TT in the population-based (β coefficients for a one standard deviation increase, 0.590; standard error (SE), 0.175; p-value, <0.01) and patient-based (β coefficient, 0.575; SE, 0.132; p-value, <0.01) samples even after adjustment for age and body mass index (both samples), and time of blood sampling (population-based sample only). Furthermore, we observed positive associations between BAP and TT (β coefficient, 0.403; SE, 0.170; p-value, 0.02) as well as between CTX and TT (β coefficient, 0.733; SE, 0.172; p-value, <0.01) in men from the general population. The present investigation shows that OCN is associated with TT in the general population and in patients with bone disorders, and may thus indicate general male health status. Additional longitudinal observational studies are warranted to confirm our findings and future experimental research is necessary to elucidate potential mechanisms underlying the observed associations.

A non-electrolyte haemolysis assay for diagnosis and prognosis of sickle cell disease

Red blood cells (RBCs) from patients with sickle cell disease (SCD) lyse in deoxygenated isosmotic non-electrolyte solutions. Haemolysis has features which suggest that it is linked to activation of the pathway termed P_sickle. This pathway is usually described as a non-specific cationic conductance activated by deoxygenation, HbS polymerisation and RBC sickling. The current work addresses the hypothesis that this haemolysis will provide a novel diagnostic and prognostic test for SCD, dependent on the altered properties of the RBC membrane resulting from HbS polymerisation. A simple test represented by this haemolysis assay would be useful especially in less affluent deprived areas of the world where SCD is most prevalent. RBCs from HbSS and most HbSC individuals showed progressive lysis in deoxygenated isosmotic sucrose solution at pH 7.4 to a level greater than that observed with RBCs from HbAS or HbAA individuals. Cytochalasin B prevented haemolysis. Haemolysis was temperature- and pH-dependent. It required near physiological temperatures to occur in deoxygenated sucrose solutions at pH 7.4. At pH 6, haemolysis occurred even in oxygenated samples. Haemolysis was reduced in patients on long-term (>5 months) hydroxyurea treatment. Several manoeuvres which stabilise soluble HbS (aromatic aldehydes o-vanillin or 5-hydroxymethyl, and urea) reduced haemolysis, an effect not due to increased oxygen affinity. Conditions designed to elicit HbS polymerisation in cells from sickle trait patients (deoxygenated hyperosmotic sucrose solutions at pH 6) supported their haemolysis. These findings are consistent with haemolysis requiring HbS polymerisation and support the hypothesis that this may be used as a test for SCD.

Screening for primary aldosteronism in hypertensive subjects: results from two German epidemiological studies

OBJECTIVE

The prevalence of primary aldosteronism in unselected hypertensive patients is currently unknown. We investigated the frequency of positive screening results for primary aldosteronism based on the aldosterone-to-renin ratio (ARR) in hypertensive subjects aged 30-79 years from two German epidemiological studies. We further examined the frequency of positive screening results in subjects with resistant hypertension or stage III hypertension and assessed possible disparities between untreated and treated hypertensive subjects.

METHODS

Data were obtained from the first follow-ups of the population-based study of health in Pomerania (SHIP; n=1392) and the cooperative health research in the region of Augsburg (KORA; n=1052). Study-specific reference ranges for plasma aldosterone concentration (PAC), plasma renin concentration (PRC) and the ARR were applied. Confirmation tests for primary aldosteronism were not performed in these epidemiological studies.Three definitions for a positive screening for primary aldosteronism were applied: A) increased ARR; B) increased ARR and decreased PRC; and C) increased ARR and increased PAC and decreased PRC.

RESULTS

The frequency of positive screening results was 7.0, 3.8 and 0.2% according to definitions A-C respectively. In the subgroups of subjects with resistant hypertension (11.9, 5.5 and 0.9%) or stage III hypertension (18.3, 14.0 and 1.1%), these frequencies were markedly higher than those in the general hypertensive population. There was no difference in the frequency of positive screening results between the treated and untreated hypertensive subjects.

CONCLUSIONS

A maximum of 7.0% of the hypertensive population in Germany shows a positive screening result for primary aldosteronism. Thus, primary aldosteronism may be less frequent than previously expected based on data from referred hypertensive patients.

Prevalence of primary aldosteronism in patient's cohorts and in population-based studies--a review of the current literature

There is an ongoing controversy on the prevalence of primary aldosteronism (PA). We aimed to update a meta-analysis published in 2008, that compiled studies reporting the prevalence of positive ARR screening tests and PA. We therefore reviewed original studies published in 2008 or later to examine whether current reports provide similar, higher or lower prevalences of elevated ARRs or PA than reports included in the original meta-analysis. A systematic review of English articles using PubMed was conducted. Search and extraction of articles were performed by one review author; the second review author checked all extracted data. We identified 11 eligible studies. The updated, weighted mean prevalences of elevated ARRs and PA in primary care (prevalence of high ARRs 16.5%; prevalence of PA 4.3%) and referred patients (prevalence of high ARRs 19.6%; prevalence of PA 9.5%) were only marginally different from the mean values obtained in the original meta-analysis. Among the current studies the maximum values for the prevalence of elevated ARRs and PA were substantially lower than among the older studies. Our results confirm the main conclusions from the original meta-analysis. The prevalence of PA increases with the severity of hypertension and the inclusion of current study results did not alter the mean prevalences of elevated ARRs and PA in primary care and referred patients. Additionally, we found that current studies focus increasingly on patients in referral centers or special subgroups, while the prevalence of PA in the general hypertensive population is yet unknown.

Association of IGF-I and the IGF-I/IGFBP-3 ratio with plasma aldosterone levels in the general population

Several studies in patients with acromegaly or growth hormone (GH) deficiency suggest a stimulatory effect of the growth hormone (GH)/insulin-like growth factor I (IGF-I) axis on the renin-angiotensin-aldosterone system (RAAS). We analyzed the association of serum IGF-I with plasma aldosterone and the aldosterone-to-renin ratio in a large sample from the general population. In addition to serum IGF-I levels, we also considered the IGF-I-to-IGF binding protein (IGFBP)-3 ratio. A total of 1 504 men and 1 566 women aged 25-88 were selected from the first follow-up of the population-based Study of Health in Pomerania. Plasma aldosterone and renin concentrations, as well as serum IGF-I and IGFBP-3 levels were determined with immunoassays. Analyses of variance and linear regression analyses were performed. We found positive associations between serum IGF-I or the IGF-I/IGFBP-3 ratio with plasma aldosterone in women but not in men. Plasma aldosterone levels increased by 2.91 ng/l per IGF-I standard deviation (SD) and by 2.17 ng/l per IGF-I/IGFBP-3 SD. The associations remained significant after exclusion of subjects taking RAAS-altering medication and of subjects with serum IGF-I levels and aldosterone-to-renin ratios outside the reference range. We conclude that, serum IGF-I and the IGF-I/IGFBP-3 ratio are associated with plasma aldosterone levels in women but not in men from the general population.

Plasma aldosterone levels and aldosterone-to-renin ratios are associated with endothelial dysfunction in young to middle-aged subjects

OBJECTIVE

Small clinical studies suggested a role for aldosterone in the development of endothelial dysfunction. We investigated whether the plasma aldosterone concentration (PAC) or the aldosterone-to-renin ratio (ARR) were associated with decreased endothelial function as measured by flow-mediated dilation (FMD) of the brachial artery in the general population.

METHODS

Our study population comprised 972 participants from the Study of Health in Pomerania, who were not treated with antihypertensive medication. We performed age-stratified (<50 and ≥ 50 years) ordinal logistic regression analyses. FMD was categorised as decreased (1st quintile), moderate (2nd-4th quintile), or increased (5th quintile). PAC and ARR were divided into low, moderate, and high values according to age- and sex-specific tertiles. All models were re-calculated for 871 subjects with PAC and ARR within the study-specific reference ranges. Odds ratios (OR) and 95% confidence intervals (CI) are presented.

RESULTS

Subjects <50 years with high PAC (OR 1.60; 95% CI 1.07-2.38) or ARR (OR 1.81; 95% CI 1.21-2.73) had higher odds for decreased FMD than subjects with low PAC or ARR, respectively. Similar results were obtained in analyses restricted to subjects with PAC and ARR within the reference range. High-normal PAC (OR 1.62; 95% CI 1.07-2.47) or ARR (OR 1.62; 95% CI 1.05-2.50) was associated with higher odds for decreased FMD when compared with low-normal PAC or ARR, respectively. These associations were not observed in subjects ≥ 50 years.

CONCLUSIONS

High and high-normal PAC or ARR contribute to an impaired FMD and subsequently the progression of subclinical atherosclerosis in young to middle-aged subjects.

Quality management in the prophylaxis of venous thrombembolism--results of a survey including 464 medical and surgical patients

BACKGROUND

We surveyed the quality of risk stratification politics and monitored the rate of entries to our company-wide protocol for venous thrombembolism (VTE) prophylaxis in order to identify safety concerns.

PATIENTS AND METHODS

Audit in 464 medical and surgical patients to evaluate quality of VTE prophylaxis.

RESULTS

Patients were classified as low 146 (31 %), medium 101 (22 %), and high risk cases 217 (47 %). Of these 262 (56.5 %) were treated according to their risk status and in accordance with our protocol, while 9 more patients were treated according to their risk status but off-protocol. Overtreatment was identified in 73 (15.7 %), undertreatment in 120 (25,9 %) of all patients. The rate of incorrect prophylaxis was significantly different between the risk categories, with more patients of the high-risk group receiving inadequate medical prophylaxis (data not shown; p = 0.038). Renal function was analyzed in 392 (84.5 %) patients. In those patients with known renal function 26 (6.6 %) received improper medical prophylaxis. If cases were added in whom prophylaxis was started without previous creatinine control, renal function was not correctly taken into account in 49 (10.6 %) of all patients. Moreover, deterioration of renal function was not excluded within one week in 78 patients (16.8 %) and blood count was not re-checked in 45 (9.7 %) of all patients after one week. There were more overtreatments in surgical (n = 53/278) and more undertreatments in medical patients (n = 54/186) (p = 0.04). Surgeons neglected renal function and blood controls significantly more often than medical doctors (p-values for both < 0.05).

CONCLUSIONS

We found a low adherence with our protocol and substantial over- and undertreatment in VTE prophylaxis. Besides, we identified disregarding of renal function and safety laboratory examinations as additional safety concerns. To identify safety problems associated with medical VTE prophylaxis and "hot spots" quality management-audits proved to be valuable instruments.

Reference intervals for aldosterone, renin, and the aldosterone-to-renin ratio in the population-based Study of Health in Pomerania (SHIP-1)

The renin-angiotensin-aldosterone system plays a key role in the regulation of human blood pressure. The aldosterone-to-renin ratio (ARR) is widely accepted for screening the primary hyperaldosteronism (PAL). Various cutoffs for positive PAL screening have been defined in patient cohorts from endocrinological referral centers and primary care. However, the distribution of the ARR in the general population is largely unknown. We aim to provide reference ranges for plasma aldosterone concentration (PAC), plasma renin concentration (PRC), and the ARR for the general population of north-east Germany. A cohort of 3 300 subjects participated in the first follow-up of the longitudinal, population-based Study of Health in Pomerania (SHIP). PAC and PRC were measured by radioimmunometric procedures. The reference interval was defined as the central 95% range between the 2.5(th) and 97.5(th) percentiles. A reference population comprising 1,347 healthy subjects was selected. Sex and age-specific (25-54 and 55-74 years) reference ranges are presented. The upper reference limit for the ARR was 14.2 and 20.3 in younger, and 22.4 and 25.5 in older men and women, respectively. Time of blood sampling had no influence on the ARR, while beta blockers, and agents acting on the renin-angiotensin system were associated with higher and lower ARR, respectively. Our upper reference limit for the ARR is clearly lower than previously reported values from studies of hypertensive patients in primary care or hypertension referral centers. We confirm that PAC and PRC are associated with various factors, including sex, age, intake of estrogen, and various antihypertensive medications.

Nonequilibrium Dynamics in Amorphous Si3B3N7

We present extensive numerical investigations of the structural relaxation dynamics of a realistic model of the amorphous high-temperature ceramic a-Si3B3N7, probing the mean-square displacement of the atoms, the bond survival probability, the average energy, the specific heat, and the two-point energy average. Combining the information from these different sources, we identify a transition temperature Tc approximately 2000 K below which the system is no longer ergodic and physical quantities observed over a time t(obs) show a systematic parametric dependence on the waiting time t(w), or age, elapsed after the quench. The aging dynamics "stiffens" as the system becomes older, which is similar to the behavior of highly idealized models such as Ising spin glasses and Lennard-Jones glasses.

Determination of symmetries and idealized cell parameters for simulated structures

A robust algorithm is presented that determines the symmetries present in an atomic configuration and idealizes the cell parameters according to the crystal system suggested by the symmetries detected. No information besides the coordinates of the atoms within some arbitrary unit cell of the crystal is required.

A New Algorithm for Space-Group Determination

An important part of the crystallographic description of crystal structures, whether they belong to synthesized compounds or have been generated by computer, is the assignment of the correct space group. Since this task often proves to be highly nontrivial, we have developed an algorithm which determines the space group and the transformation to the standard setting of a given crystal structure, where no restrictions are placed on the original description of the structure.

Enterocytozoon bieneusi infection in an immunocompetent patient who had acute diarrhea and who was not infected with the human immunodeficiency virus

Enterocytozoon bieneusi is a microsporidian species that has been detected exclusively in patients infected with human immunodeficiency virus (HIV) who are severely immunocompromised. We report what we believe is the first case of E. bieneusi infection in an HIV-negative patient with acute, self-limited diarrhea whose CD4+ cell count was not depressed.